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    <title>操作系统课程设计 – ruokeqx&#39;s blog</title>
    


  
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    <h2 class="single__title" data-ani="true">操作系统课程设计</h2>
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  <time class="single__info" title="Written At">📅&nbsp;Nov 26, 2021 </time>
  
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      <h2 id="前言">前言</h2>
<p>操作系统课设上来就是远古版本2.4kernel，原地怀疑题目是不是复用了十多年了。虽然疯狂吐槽 还是想编译试试看.</p>
<p>要求添加系统调用，想着是准备做一个内核流量捕获的简单工具，于是简单的了解了一下捕获流量的方法，看了一下libpcap和tcpdump的源码，了解了mapped memory和ring buffer的使用直接从网卡驱动摘下流量极大减少系统负载，但是由于事件仓促，最后却只是草草地写了个简单的系统调用版本并编译进内核使用qemu调试配合ping进行测试。</p>
<h2 id="begin">Begin</h2>
<p>要增加对某部分功能的支持，比如网络之类，可以把相应部分编译到内核中（build-in），也可以把该部分编译成模块（module），动态调用。如果编译到内核中，在内核启动时就可以自动支持相应部分的功能，这样的优点是方便、速度快，机器一启动，你就可以使用这部分功能了；缺点是会使内核变得庞大起来，不管你是否需要这部分功能，它都会存在，建议经常使用的部分直接编译到内核中，比如网卡。如果编译成模块，就会生成对应的.o文件，在使用的时候可以动态加载，优点是不会使内核过分庞大，缺点是你得自己来调用这些模块。</p>
<p>环境</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">Linux ruokeqx 4.4.0-142-generic <span class="c1">#168~14.04.1-Ubuntu SMP Sat Jan 19 11:26:28 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux</span>
</code></pre></td></tr></table>
</div>
</div><p>克隆内核源码（第二个链接会快点）</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">git clone https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/linux-2.4.git/
git clone https://kernel.googlesource.com/pub/scm/linux/kernel/git/wtarreau/linux-2.4
</code></pre></td></tr></table>
</div>
</div><p>安装编译环境</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">sudo apt install git fakeroot build-essential ncurses-dev xz-utils libssl-dev bc flex libelf-dev bison
</code></pre></td></tr></table>
</div>
</div><p><code>make menuconfig</code>将打开一个配置工具，它可以让你遍历每个可用模块，然后启用或者禁用你需要或者不需要的模块。此处选择默认直接保存。</p>
<p>尝试编译，报错如下：</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1">#error &#34;GCC &gt;= 4.2 miscompiles kernel 2.4, do not use it!&#34;</span>
</code></pre></td></tr></table>
</div>
</div><p>需要版本小于4.2的GCC</p>
<h2 id="编译">编译</h2>
<h3 id="编译安装gcc412">编译安装GCC4.1.2</h3>
<p>GCC官网下载源码http://ftp.gnu.org/gnu/gcc/gcc-4.1.2/gcc-4.1.2.tar.bz2</p>
<p>安装依赖</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">sudo apt-get install libc6-dev libgmp-dev libmpfr-dev texinfo
</code></pre></td></tr></table>
</div>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="nb">cd</span> /usr/include
sudo ln -s x86_64-linux-gnu/bits bits
sudo ln -s x86_64-linux-gnu/gnu gnu
sudo ln -s x86_64-linux-gnu/sys sys
sudo ln -s x86_64-linux-gnu/asm asm
<span class="nb">cd</span> /usr/lib
sudo ln -s x86_64-linux-gnu/crt1.o crt1.o
sudo ln -s x86_64-linux-gnu/crti.o crti.o
sudo ln -s x86_64-linux-gnu/crtn.o crtn.o
</code></pre></td></tr></table>
</div>
</div><p>编译GCC</p>
<p>此处前半部分尝试使用<code>ubuntu18.04</code> <code>gcc7.x</code>编译，后来问题很多改用<code>ubuntu14.04</code> <code>gcc4.8.4</code>编译通过。</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">$ <span class="nb">cd</span> gcc-4.0.0
$ mkdir build
$ <span class="nb">cd</span> build
$ ../configure --prefix<span class="o">=</span>/usr/local --program-prefix<span class="o">=</span>sse- --libexecdir<span class="o">=</span>/usr/local/lib --enable-shared --enable-threads<span class="o">=</span>posix --enable-__cxa_atexit --enable-clocale<span class="o">=</span>gnu --disable-multilib --enable-languages<span class="o">=</span>c,c++
$ make bootstrap <span class="nv">MAKEINFO</span><span class="o">=</span>makeinfo
</code></pre></td></tr></table>
</div>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">../../gcc/toplev.c:547:1: error: redefinition of ‘floor_log2’
 floor_log2 <span class="o">(</span>unsigned HOST_WIDE_INT x<span class="o">)</span>
 ../../gcc/toplev.c:582:1: error: redefinition of ‘exact_log2’
 exact_log2 <span class="o">(</span>unsigned HOST_WIDE_INT x<span class="o">)</span>
</code></pre></td></tr></table>
</div>
</div><p><a href="https://stackoverflow.com/questions/34569458/error-occurred-compiling-gcc-from-source-code">https://stackoverflow.com/questions/34569458/error-occurred-compiling-gcc-from-source-code</a></p>
<p>修改Makefile</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="nv">CC</span> <span class="o">=</span> gcc -fgnu89-inline
<span class="nv">CXX</span> <span class="o">=</span> g++ -fgnu89-inline
</code></pre></td></tr></table>
</div>
</div><p>Make再次出错</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">In <span class="k">function</span> ‘open’,
    inlined from ‘collect_execute’ at ../../gcc/collect2.c:1577:20:
/usr/include/x86_64-linux-gnu/bits/fcntl2.h:50:4: error: call to ‘__open_missing_mode’ declared with attribute error: open with O_CREAT or O_TMPFILE in second argument needs <span class="m">3</span> arguments
    __open_missing_mode <span class="o">()</span><span class="p">;</span>
</code></pre></td></tr></table>
</div>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"> ~/project/gcc-4.0.0/gcc &gt; vim collect2.c +1577

<span class="nv">redir_handle</span> <span class="o">=</span> open <span class="o">(</span>redir, O_WRONLY <span class="p">|</span> O_TRUNC <span class="p">|</span> O_CREAT, 0777<span class="o">)</span><span class="p">;</span> 
</code></pre></td></tr></table>
</div>
</div><p>（后续还有好多问题，暂时放弃。。</p>
<p>折回原位，选用<code>ubuntu14.04</code>，自带gcc版本4.8.4，按照上面的修改Makefile两行即可直接编译一遍过。</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">sudo make install
sudo ln -sf /usr/local/bin/x86_64-unknown-linux-gnu-gcc-4.1.2 /usr/bin/gcc
sudo ln -sf /usr/local/bin/x86_64-unknown-linux-gnu-sse-g++ /usr/bin/g++
</code></pre></td></tr></table>
</div>
</div><p>验证安装</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">ruokeqx@ruokeqx:~$ gcc --version
gcc <span class="o">(</span>GCC<span class="o">)</span> 4.1.2
Copyright <span class="o">(</span>C<span class="o">)</span> <span class="m">2006</span> Free Software Foundation, Inc.
This is free software<span class="p">;</span> see the <span class="nb">source</span> <span class="k">for</span> copying conditions.  There is NO
warranty<span class="p">;</span> not even <span class="k">for</span> MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

ruokeqx@ruokeqx:~$ g++ --version
g++ <span class="o">(</span>GCC<span class="o">)</span> 4.1.2
Copyright <span class="o">(</span>C<span class="o">)</span> <span class="m">2006</span> Free Software Foundation, Inc.
This is free software<span class="p">;</span> see the <span class="nb">source</span> <span class="k">for</span> copying conditions.  There is NO
warranty<span class="p">;</span> not even <span class="k">for</span> MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

ruokeqx@ruokeqx:~$ 
</code></pre></td></tr></table>
</div>
</div><h3 id="编译linux-24">编译linux-2.4</h3>
<p>此前已经clone好2.4的源码，并已经在编译gcc时创建部分软链接</p>
<p>下面部分代码创建软链接在我看的教程中说是确保这些链接是指向要升级的内核源代码（他事先删除了这个目录自带的），我的系统刚装没有动过就直接用自带的 <code>linux</code>和<code>scsi</code>的目录了（<code>asm</code>好像是上面编译gcc时创建的软链接）</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># 四舍五入这里用不到（doge</span>
<span class="nb">cd</span> /usr/include
<span class="c1"># rm -r asm linux scsi</span>
<span class="c1"># 这里软链接还是用之前编译gcc用到的asm，下面这条编译会报错没有asm/boot.h</span>
<span class="c1"># sudo ln -s /usr/src/linux-headers-4.4.0-142/include/asm-generic asm</span>
<span class="c1"># 这里下面两个系统自带了</span>
<span class="c1"># sudo ln -s /usr/src/linux-headers-4.4.0-142/include/linux linux</span>
<span class="c1"># sudo ln -s /usr/src/linux-headers-4.4.0-142/include/scsi scsi</span>
</code></pre></td></tr></table>
</div>
</div><p>配置内核，这部分还是特别重要且相对麻烦的 [具体看链接8]，但是由于与本次实验无关，所以直接使用默认值了。</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">make config		<span class="c1">#（基于文本的最为传统的配置界面，不推荐使用）</span>
make menuconfig	<span class="c1">#（基于文本选单的配置界面，字符终端下推荐使用）</span>
make xconfig	<span class="c1">#（基于图形窗口模式的配置界面，Xwindow下推荐使用）</span>
make oldconfig	<span class="c1">#（如果只想在原来内核配置的基础上修改一些小地方，会省去不少麻烦）</span>
</code></pre></td></tr></table>
</div>
</div><p>编译</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># 读取配置生成的配置文件 来创建对应于配置的依赖关系树</span>
make dep
<span class="c1"># 删除前面步骤留下的文件</span>
make clean
<span class="c1"># 完全编译内核</span>
make bzImage
<span class="c1"># 后面三个命令只有在你进行配置的过程中，在回答Enable loadable module support (CONFIG_MODULES)时选了&#34;Yes&#34;才是必要的，默认是[*] built-in</span>
<span class="c1"># make modules和make modules_install分别生成相应的模块和把模块拷贝到需要的目录中</span>
make modules
sudo make modules_install
<span class="c1"># 生成模块间的依赖关系，启动新内核之后，使用modprobe命令加载模块时就能正确地定位模块</span>
depmod -a
</code></pre></td></tr></table>
</div>
</div><p>编译时报错如下，变量未声明，github搜变量名看到值都是0X7F00，于是编辑源码加上一句，编译成功。</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">tools/build.c:155:error: ‘DEF_SYSSIZE’ undeclared <span class="o">(</span>first use in this <span class="k">function</span><span class="o">)</span>

vim <span class="o">[</span><span class="nb">source</span> path<span class="o">]</span>/arch/x86_64/boot/tools/build.c +37
<span class="c1">#define DEF_SYSSIZE 0x7F00</span>
</code></pre></td></tr></table>
</div>
</div><p>编译成功（也只能说仅仅是编译成功了，具体继续往下看），文件路径为</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="o">[</span><span class="nb">source</span> path<span class="o">]</span>/System.map
<span class="o">[</span><span class="nb">source</span> path<span class="o">]</span>/arch/x86_64/boot/bzImage
</code></pre></td></tr></table>
</div>
</div><h2 id="qemu内核运行及调试">qemu内核运行及调试</h2>
<p>安装qemu</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">cp linux-2.4/arch/x86_64/boot/bzImage ./
sudo apt install qemu
</code></pre></td></tr></table>
</div>
</div><p>制作<code>initrd(initial ramdisk)</code>, 在内核启动的时候会先去加载的一种文件系统[见参考14]</p>
<p>[If you have Linux Kernel 2.4 or later, you already have support of ramdisk built in.] kernel2.4刚好是支持ramdisk的最早版本</p>
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<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="cp">#include</span> <span class="cpf">&lt;stdio.h&gt;</span><span class="cp">
</span><span class="cp"></span>
<span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;hello ruokeqx&#34;</span><span class="p">);</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;hello ruokeqx&#34;</span><span class="p">);</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;hello ruokeqx&#34;</span><span class="p">);</span>
        <span class="n">fflush</span><span class="p">(</span><span class="n">stdout</span><span class="p">);</span>
        <span class="k">while</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span>
        <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
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</div>
</div><p>静态编译并运行</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">gcc -static -o helloworld hello.c
<span class="nb">echo</span> helloworld <span class="p">|</span> cpio -o --format<span class="o">=</span>newc &gt; rootfs
</code></pre></td></tr></table>
</div>
</div><p>常规操作应该是使用<code>busybox</code>:[嵌入式linux的瑞士军刀，包含基本命令] 来构建文件系统，然后再qemu运行。</p>
<p>但是 <code>qemu</code>的<code>-kernel</code>和<code>-initrd</code>能够绕过<code>bootload</code>直接对指定的<code>kernel</code>和<code>ramdisk</code>进行加载，上面echo那行命令就是创建<code>cpio-initrd</code>的过程。</p>
<h3 id="运行中的亿点问题">运行中的亿点问题</h3>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">&gt; qemu-system-x86_64 -kernel ./bzImage -initrd ./rootfs -append <span class="s2">&#34;root=/dev/ram rdinit=/helloworld&#34;</span>
<span class="c1"># 报错如下</span>
RAMDISK: Couldn<span class="err">&#39;</span>t find valid RAM disk image starting at 0.
VFS: Cannot open root device <span class="s2">&#34;ram&#34;</span> or 08:01
Please append a correct <span class="s2">&#34;root=&#34;</span> boot option
Kernel panic: VFS: Unable to mount root fs on 08:01
</code></pre></td></tr></table>
</div>
</div><p>发现我的系统没有<code>/dev/ram</code>，查找<code>/dev</code>下设备文件意义得到如下</p>
<pre tabindex="0"><code>1 block   RAM disk   [已过时，请用TMPFS]
          0 = /dev/ram0        第1个 RAM disk
          1 = /dev/ram1        第2个 RAM disk
[说明]将/dev/ram0用作initrd的做法已过时(因为它仅针对image-initrd格式)，当下的主流是cpio-initrd格式。

以下目录被保留用于挂载特殊的文件系统。这些特殊的文件系统只提供内核接口而不提供标准的设备节点。
/dev/shm        tmpfs           提供对 POSIX 共享内存的直接访问
</code></pre><p>于是尝试</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">sudo qemu-system-x86_64 -kernel ./bzImage -initrd ./rootfs -append <span class="s2">&#34;root=/dev/shm rdinit=/helloworld&#34;</span>
</code></pre></td></tr></table>
</div>
</div><p>还是相同报错，只不过上面的<code>ram</code>变成了<code>shm</code>.</p>
<p>尝试过换到ubuntu18.04，依旧是一堆报错</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">WARNING: Image format was not specified <span class="k">for</span> <span class="s1">&#39;rootfs&#39;</span> and probing guessed raw.
         Automatically detecting the format is dangerous <span class="k">for</span> raw images, write operations on block <span class="m">0</span> will be restricted.
         Specify the <span class="s1">&#39;raw&#39;</span> format explicitly to remove the restrictions.
         
<span class="c1">#	-drive format=raw,file=rootfs</span>
</code></pre></td></tr></table>
</div>
</div><p>虚拟化问题</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">warning: TCG doesn<span class="err">&#39;</span>t support requested feature: CPUID.01H:ECX.vmx <span class="o">[</span>bit 5<span class="o">]</span>

<span class="c1"># 虚拟机处理器开启 虚拟化 Intel VT-x/EPT 或 AMD-V/RVI(V)</span>
</code></pre></td></tr></table>
</div>
</div><p>制作磁盘镜像</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># qemu-img 创建一个磁盘镜像文件</span>
qemu-img create -f raw disk.raw 512M
<span class="c1"># 格式化为ext4</span>
mkfs -t ext4 ./disk.raw
<span class="c1"># 挂在磁盘镜像文件，这样就可以操作磁盘镜像文件中的内容了</span>
sudo mount -o loop ./disk.raw ./img
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">Kernel panic: Attempted to <span class="nb">kill</span> the idle task!
In idle task - not syncing

Kernel panic: Attempted to <span class="nb">kill</span> init!
</code></pre></td></tr></table>
</div>
</div><h3 id="放弃initrd运行kernel24">放弃initrd运行kernel2.4</h3>
<p>一堆问题，自闭了。</p>
<p>看了一道朋友博客的<code>kernelpwn</code>题，拿到附件用他的环境尝试运行我的程序，发现成功。步骤如下</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># 现成内核和rootfs.cpio运行编译好的程序helloworld</span>
ls
babydriver.i64  babydriver.tar.xz  boot.sh  bzImage  rootfs.cpio
mkdir tmp
cp rootfs.cpio ./tmp/rootfs.cpio.gz
<span class="nb">cd</span> tmp/
gunzip ./rootfs.cpio.gz
cpio -idmv &lt; rootfs.cpio
....
ls
....
cp ../../helloworld ./
<span class="nb">echo</span> /helloworld &gt; init
find . <span class="p">|</span> cpio -o --format<span class="o">=</span>newc &gt; rootfs.cpio
mv rootfs.cpio ../
<span class="nb">cd</span> ..
./boot.sh
</code></pre></td></tr></table>
</div>
</div><p>然后用他的<code>bzImgae</code>替换我的程序后成功运行</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="nb">echo</span> helloworld <span class="p">|</span> cpio -o --format<span class="o">=</span>newc &gt; rootfs
cp kernelpwn/bzImage ./
qemu-system-x86_64 <span class="se">\
</span><span class="se"></span>	-kernel ./bzImage <span class="se">\
</span><span class="se"></span>	-initrd ./rootfs <span class="se">\
</span><span class="se"></span>	-append <span class="s2">&#34;root=/dev/ram rdinit=/helloworld&#34;</span>
</code></pre></td></tr></table>
</div>
</div><p><img src="/images/posts/%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211126155106914.png" alt="image-20211126155106914" /></p>
<p>那么现在可以确定是我编译的内核有问题（</p>
<p>看了https://wiki.debian.org/Initrd后，发现kernel2.4只支持<code>block-disk image</code>，不支持<code>cpio archive</code>，需要用<code>mkinitrd</code>创建镜像，而<code>ubuntu14.04</code>都只自带<code>initramfs</code>而没<code>mkinitrd</code>，似乎连apt源中都移除了<code>initrd-tools</code>；好像也跟发行版有关系，<code>centos7</code>中还使用<code>mkinitrd</code>.</p>
<pre tabindex="0"><code>Kernel up to 2.4 were expecting the initrd file to be a (compressed) block-disk image (i.e formated as ext2 or minix fs). the initrd was created using mkinitrd.
Kernel 2.6 is expecting the initrd file to be a (compressed) cpio archive, to be uncompressed in a ramdisk, known as initramfs.
</code></pre><p>至少可以确定的是在<code>debian</code>系近十年的发行版中编译并用<code>initrd</code>运行<code>kernel2.4</code>几乎是不可能的（</p>
<h3 id="尝试使用busybox">尝试使用busybox</h3>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">qemu-img create -f raw disk.raw 512M
mkfs -t ext2 ./disk.raw
mkdir img
sudo mount -o loop ./disk.raw ./img
<span class="c1"># 刚才kernelpwn的题目自带的busybox直接拷贝过来</span>
sudo cp -r tmp/* ./img/
qemu-system-x86_64 -m 512M -smp <span class="m">4</span> -kernel bzImage.2.4 -drive <span class="nv">format</span><span class="o">=</span>raw,file<span class="o">=</span>./disk.raw --append <span class="s2">&#34;init=/linuxrc root=/dev/sda&#34;</span>
</code></pre></td></tr></table>
</div>
</div><p>kernel2.4仍然报错</p>
<pre tabindex="0"><code>reiserfs_read_super can not find reiserfs on ramdisk(1,0)


Kernel panic: Attempted to kill init!
</code></pre><p>尝试kernel2.6（这里的镜像是后面initrd运行kernel2.6编译的）</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">qemu-system-x86_64 -m 512M -smp <span class="m">4</span> -kernel bzImage.2.6 -drive <span class="nv">format</span><span class="o">=</span>raw,file<span class="o">=</span>./disk.raw --append <span class="s2">&#34;init=/linuxrc root=/dev/sda&#34;</span>

can<span class="s1">&#39;t open /dev/tty2: No such file or directory
</span><span class="s1">can&#39;</span>t open /dev/tty3: No such file or directory
can<span class="err">&#39;</span>t open /dev/tty4: No such file or directory
</code></pre></td></tr></table>
</div>
</div><p>busybox init启动后会扫描<code>/etc/inittab</code> ，没有的话就用下面的默认配置，所以会tty报错</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">::sysinit:/etc/init.d/rcS
::askfirst:/bin/sh
::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r
::restart:/sbin/init
tty2::askfirst:/bin/sh
tty3::askfirst:/bin/sh
tty4::askfirst:/bin/sh
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</div><p>我们创建文件内容</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># /etc/inittab</span>
::sysinit:/etc/init.d/rcS
::askfirst:/bin/ash
::ctrlaltdel:/sbin/reboot
::shutdown:/sbin/swapoff -a
::shutdown:/bin/umount -a -r
::restart:/sbin/init
<span class="c1"># /etc/init.d/rcS</span>
<span class="c1">#!/bin/sh</span>
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</div><p>kernel2.6成功运行</p>
<p><img src="/images/posts/%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211126203526682.png" alt="image-20211126203526682" /></p>
<h3 id="尝试initrd运行kernel26">尝试initrd运行kernel2.6</h3>
<p>gcc换回4.8.4直接一遍编译成功</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">make menuconfig
make
make bzImage
cp arch/x86_64/boot/bzImage ./
cp bzImage ../bzImage2.6
qemu-system-x86_64 -kernel ./bzImage.2.6 -initrd ./rootfs -append <span class="s2">&#34;root=/dev/shm rdinit=/helloworld&#34;</span>
</code></pre></td></tr></table>
</div>
</div><p><img src="/images/posts/%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211126192047362.png" alt="image-20211126192047362" /></p>
<h3 id="编写shell脚本">编写shell脚本</h3>
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<pre tabindex="0" class="chroma"><code class="language-shell" data-lang="shell"><span class="cp">#!/bin/sh
</span><span class="cp"></span>
<span class="nb">cd</span> linux-5.15.6
<span class="k">if</span> <span class="o">[</span> <span class="nv">$1</span> <span class="o">]</span><span class="p">;</span> <span class="k">then</span>
	make -j12
<span class="k">fi</span>
<span class="c1"># make bzImage</span>
cp arch/x86/boot/bzImage ../
<span class="nb">cd</span> ..

gcc -static -o fs/ruokeqx check_syscall.c -g
<span class="c1">#gcc -static -o fs/ruokeqx cap.c -g</span>

<span class="nb">cd</span> fs
find . -print0 <span class="p">|</span> cpio --null -ov --format<span class="o">=</span>newc <span class="p">|</span> gzip -9 &gt; ../init.cpio.gz
<span class="c1"># find ruokeqx | cpio -o --format=newc &gt; rootfs.cpio</span>
<span class="nb">cd</span> ..

qemu-system-x86_64 <span class="se">\
</span><span class="se"></span>	-kernel bzImage  <span class="se">\
</span><span class="se"></span>	-initrd init.cpio.gz <span class="se">\
</span><span class="se"></span>	-nographic <span class="se">\
</span><span class="se"></span>	-S -s <span class="se">\
</span><span class="se"></span>	-net nic <span class="se">\
</span><span class="se"></span>	-net tap,ifname<span class="o">=</span>tap0,script<span class="o">=</span>no,downscript<span class="o">=</span>no <span class="se">\
</span><span class="se"></span>	-append <span class="s2">&#34;console=ttyS0 nokaslr&#34;</span> <span class="se">\
</span><span class="se"></span>	<span class="c1"># -S -s # gdbserver</span>
	<span class="c1">#-append &#34;console=ttyS0 rdinit=/ruokeqx&#34;</span>
</code></pre></td></tr></table>
</div>
</div><h2 id="内核源码阅读">内核源码阅读</h2>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash"><span class="c1"># linux-5.9/include/uapi/linux/if_ether.h</span>
struct ethhdr <span class="o">{}</span> __attribute__<span class="o">((</span>packed<span class="o">))</span><span class="p">;</span>
<span class="c1"># linux-5.9/include/uapi/linux/ip.h</span>
struct iphdr <span class="o">{}</span><span class="p">;</span>
<span class="c1"># linux-5.9/include/uapi/linux/if_arp.h</span>
struct arphdr <span class="o">{}</span><span class="p">;</span>
<span class="c1"># linux-5.9/net/socket.c</span>
int __sys_recvfrom<span class="o">(</span>int fd, void __user *ubuf, size_t size, unsigned int flags,
		   struct sockaddr __user *addr, int __user *addr_len<span class="o">)</span>
</code></pre></td></tr></table>
</div>
</div><h2 id="添加系统调用">添加系统调用</h2>
<p>要添加系统调用大体需要三步<br />
1.先在<code>arch/x86/entry/syscalls/syscall_64.tbl</code>中分配调用号<br />
2.在<code>include/linux/syscalls.h</code>定义系统调用<br />
3.在内核任意区域添加<code>SYSCALL_DEFINE</code>并给出具体实现</p>
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<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="c1">// 系统调用表
</span><span class="c1">// linux-5.9/arch/x86/entry/syscalls/syscall_64.tbl
</span><span class="c1">// # The format is:
</span><span class="c1">// # &lt;number&gt; &lt;abi&gt; &lt;name&gt; &lt;entry point&gt;
</span><span class="c1">// #    45	   64  recvfrom sys_recvfrom
</span><span class="c1">// 系统调用定义文件
</span><span class="c1">// linux-5.9/kernel/sys.c
</span><span class="c1">// 服务例程的原型声明
</span><span class="c1">// linux-5.9/include/linux/syscalls.h
</span><span class="c1"></span><span class="cm">/* net/socket.c */</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_socket</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_socketpair</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_bind</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_listen</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_accept</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_connect</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_getsockname</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_getpeername</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_sendto</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">void</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="n">size_t</span><span class="p">,</span> <span class="kt">unsigned</span><span class="p">,</span>
				<span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_recvfrom</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">void</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="n">size_t</span><span class="p">,</span> <span class="kt">unsigned</span><span class="p">,</span>
				<span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_setsockopt</span><span class="p">(</span><span class="kt">int</span> <span class="n">fd</span><span class="p">,</span> <span class="kt">int</span> <span class="n">level</span><span class="p">,</span> <span class="kt">int</span> <span class="n">optname</span><span class="p">,</span>
				<span class="kt">char</span> <span class="n">__user</span> <span class="o">*</span><span class="n">optval</span><span class="p">,</span> <span class="kt">int</span> <span class="n">optlen</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_getsockopt</span><span class="p">(</span><span class="kt">int</span> <span class="n">fd</span><span class="p">,</span> <span class="kt">int</span> <span class="n">level</span><span class="p">,</span> <span class="kt">int</span> <span class="n">optname</span><span class="p">,</span>
				<span class="kt">char</span> <span class="n">__user</span> <span class="o">*</span><span class="n">optval</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="n">optlen</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_shutdown</span><span class="p">(</span><span class="kt">int</span><span class="p">,</span> <span class="kt">int</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_sendmsg</span><span class="p">(</span><span class="kt">int</span> <span class="n">fd</span><span class="p">,</span> <span class="k">struct</span> <span class="n">user_msghdr</span> <span class="n">__user</span> <span class="o">*</span><span class="n">msg</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="n">flags</span><span class="p">);</span>
<span class="n">asmlinkage</span> <span class="kt">long</span> <span class="nf">sys_recvmsg</span><span class="p">(</span><span class="kt">int</span> <span class="n">fd</span><span class="p">,</span> <span class="k">struct</span> <span class="n">user_msghdr</span> <span class="n">__user</span> <span class="o">*</span><span class="n">msg</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="n">flags</span><span class="p">);</span>
</code></pre></td></tr></table>
</div>
</div><p>注意点</p>
<pre tabindex="0"><code>kernel
不同的函数
printk()
kmalloc(size,mem_type)
kfree()

for(int i=0;i&lt;10;++i)的写法是错的 c语言版本不支持在for中定义


查看内核日志
sudo dmesg

跟踪程序系统调用
sudo strace sudo ./check_syscall

</code></pre><h3 id="源码">源码</h3>
<p>net/socket.c</p>
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<td class="lntd">
<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="cp">#include</span> <span class="cpf">&lt;linux/if_ether.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/ip.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/tcp.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/udp.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/if_arp.h&gt;</span><span class="cp">
</span><span class="cp"></span><span class="c1">// #include &lt;stdio.h&gt;
</span><span class="c1">// #include &lt;stdlib.h&gt;
</span><span class="c1"></span>


<span class="c1">//参考内核 struct ethhdr 定义 (include/uapi/linux/if_ether.h）
</span><span class="c1">//参考内核 struct iphdr 定义（include/uapi/linux/ip.h）
</span><span class="c1">//参考内核 struct tcphdr 定义（include/uapi/linux/tcp.h）
</span><span class="c1">//参考内核 struct udphdr 定义（include/uapi/linux/udp.h）
</span><span class="c1">//参考内核 struct arphdr 定义（include/uapi/linux/if_arp.h）
</span><span class="c1"></span><span class="k">struct</span> <span class="n">struct_packet</span> <span class="p">{</span>
	<span class="kt">unsigned</span> <span class="kt">char</span>	<span class="n">mac_dest</span><span class="p">[</span><span class="n">ETH_ALEN</span><span class="p">];</span>
	<span class="kt">unsigned</span> <span class="kt">char</span>	<span class="n">mac_source</span><span class="p">[</span><span class="n">ETH_ALEN</span><span class="p">];</span>
	<span class="n">__be16</span>		<span class="n">eth_proto</span><span class="p">;</span>		<span class="cm">/* packet type ID field	*/</span>
	<span class="n">__be32</span>	<span class="n">ip_source</span><span class="p">;</span>
	<span class="n">__be32</span>	<span class="n">ip_dest</span><span class="p">;</span>
	<span class="c1">// tools/include/uapi/linux/in.h
</span><span class="c1"></span>	<span class="c1">// 1icmp/2igmp/6tcp/17udp
</span><span class="c1"></span>	<span class="n">__u8</span>	<span class="n">ip_proto</span><span class="p">;</span>
	<span class="n">__be16</span>	<span class="n">port_source</span><span class="p">;</span>
	<span class="n">__be16</span>	<span class="n">port_dest</span><span class="p">;</span>
<span class="p">};</span>


<span class="c1">// unsigned int htonl(unsigned int	x)
</span><span class="c1">// {
</span><span class="c1">// 	unsigned int  y;
</span><span class="c1">// 	((unsigned char*)&amp;y)[0]= ((unsigned char*)&amp;x)[3];
</span><span class="c1">// 	((unsigned char*)&amp;y)[1]= ((unsigned char*)&amp;x)[2];
</span><span class="c1">// 	((unsigned char*)&amp;y)[2]= ((unsigned char*)&amp;x)[1];
</span><span class="c1">// 	((unsigned char*)&amp;y)[3]= ((unsigned char*)&amp;x)[0];
</span><span class="c1">// 	return y;
</span><span class="c1">// }
</span><span class="c1">// unsigned short htons(unsigned short x)
</span><span class="c1">// {
</span><span class="c1">// 	unsigned short y;
</span><span class="c1">// 	((unsigned char*)&amp;y)[0]= ((unsigned char*)&amp;x)[1];
</span><span class="c1">// 	((unsigned char*)&amp;y)[1]= ((unsigned char*)&amp;x)[0];
</span><span class="c1">// 	return y;
</span><span class="c1">// }
</span><span class="c1"></span>


<span class="cm">/*
</span><span class="cm">	char * memp pointer for data
</span><span class="cm">	int caplen cap number of packet
</span><span class="cm">	return -1 on error 0 for success
</span><span class="cm">*/</span>
<span class="kt">int</span> <span class="nf">__sys_cap</span><span class="p">(</span><span class="kt">char</span> <span class="o">*</span> <span class="n">memp</span><span class="p">,</span> <span class="kt">int</span> <span class="n">caplen</span><span class="p">)</span>
<span class="p">{</span>
<span class="cp">#ifndef BUFFER_MAX
</span><span class="cp">#define BUFFER_MAX 4096
</span><span class="cp">#endif
</span><span class="cp"></span>	<span class="kt">int</span> <span class="n">len</span><span class="p">,</span><span class="n">i</span><span class="p">;</span>
	<span class="kt">int</span>	<span class="n">sock</span><span class="p">;</span>
	<span class="c1">// https://www.kernel.org/doc/htmldocs/kernel-api/API-kmalloc.html
</span><span class="c1"></span>	<span class="c1">// https://www.kernel.org/doc/htmldocs/kernel-api/API-kfree.html
</span><span class="c1"></span>	<span class="kt">char</span> <span class="o">*</span> <span class="n">buffer</span> <span class="o">=</span> <span class="n">kmalloc</span><span class="p">(</span><span class="n">BUFFER_MAX</span><span class="p">,</span> <span class="n">GFP_KERNEL</span><span class="p">);</span>

	<span class="k">struct</span> <span class="n">struct_packet</span> <span class="o">*</span><span class="n">s_packet</span><span class="p">;</span>
	<span class="k">struct</span> <span class="n">ethhdr</span> <span class="o">*</span><span class="n">mac_hdr</span><span class="p">;</span>
	<span class="k">struct</span> <span class="n">iphdr</span> <span class="o">*</span><span class="n">ip_hdr</span><span class="p">;</span>
	<span class="k">struct</span> <span class="n">tcphdr</span> <span class="o">*</span><span class="n">tcp_hdr</span><span class="p">;</span>
	<span class="k">struct</span> <span class="n">udphdr</span> <span class="o">*</span><span class="n">udp_hdr</span><span class="p">;</span>
	<span class="k">struct</span> <span class="n">arphdr</span> <span class="o">*</span><span class="n">arp_hdr</span><span class="p">;</span>

	<span class="k">if</span><span class="p">(</span> <span class="p">(</span><span class="n">sock</span> <span class="o">=</span> <span class="n">__sys_socket</span><span class="p">(</span><span class="n">PF_PACKET</span><span class="p">,</span> <span class="n">SOCK_RAW</span><span class="p">,</span> <span class="n">htons</span><span class="p">(</span><span class="n">ETH_P_ALL</span><span class="p">)))</span> <span class="o">&lt;</span> <span class="mi">0</span> <span class="p">){</span>
		<span class="n">printk</span><span class="p">(</span><span class="s">&#34;Create socket error.</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
		<span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
		<span class="c1">// exit(0);
</span><span class="c1"></span>	<span class="p">}</span>

	<span class="k">while</span><span class="p">(</span><span class="n">caplen</span><span class="o">--</span><span class="p">){</span>
		<span class="n">len</span> <span class="o">=</span> <span class="n">__sys_recvfrom</span><span class="p">(</span><span class="n">sock</span><span class="p">,</span> <span class="n">buffer</span><span class="p">,</span> <span class="n">BUFFER_MAX</span><span class="p">,</span> <span class="mi">0</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">,</span> <span class="nb">NULL</span><span class="p">);</span>
		<span class="n">printk</span><span class="p">(</span><span class="s">&#34;len:%d&#34;</span><span class="p">,</span><span class="n">len</span><span class="p">);</span>
		<span class="k">for</span><span class="p">(</span><span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="n">len</span><span class="p">;</span><span class="o">++</span><span class="n">i</span><span class="p">){</span>
			<span class="n">printk</span><span class="p">(</span><span class="s">&#34;%02x &#34;</span><span class="p">,(</span><span class="kt">unsigned</span> <span class="kt">char</span><span class="p">)</span><span class="n">buffer</span><span class="p">[</span><span class="n">i</span><span class="p">]);</span>
		<span class="p">}</span>
		<span class="k">if</span> <span class="p">(</span><span class="n">len</span> <span class="o">&lt;</span> <span class="mi">46</span><span class="p">)</span> <span class="p">{</span>
			<span class="n">printk</span><span class="p">(</span><span class="s">&#34;Catch packet length error.</span><span class="se">\n</span><span class="s">&#34;</span> <span class="p">);</span>
			<span class="n">__sys_shutdown</span><span class="p">(</span><span class="n">sock</span><span class="p">,</span> <span class="mi">2</span><span class="p">);</span>
			<span class="c1">// close(sock);
</span><span class="c1"></span>			<span class="k">return</span> <span class="o">-</span><span class="mi">1</span><span class="p">;</span>
			<span class="c1">// exit(0);
</span><span class="c1"></span>		<span class="p">}</span>

		<span class="c1">// copy_to_user(memp, ,);
</span><span class="c1"></span>		<span class="c1">// printk(&#34;截获内容长度 %d\n&#34;, len);
</span><span class="c1"></span>

		<span class="c1">// sizeof(struct ethhdr) = 14
</span><span class="c1"></span>		<span class="c1">// sizeof(struct ipdhr) = 20
</span><span class="c1"></span>		<span class="c1">// sizeof(struct arpdhr) = 28	6 4 Sender_ip 6 4 Target_ip
</span><span class="c1"></span>		<span class="n">mac_hdr</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">ethhdr</span> <span class="o">*</span><span class="p">)</span><span class="n">buffer</span><span class="p">;</span>
		<span class="n">s_packet</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">struct_packet</span> <span class="o">*</span><span class="p">)</span><span class="n">mac_hdr</span><span class="p">;</span>


		<span class="cm">/*
</span><span class="cm">		s_packet-&gt;mac_dest[0] = mac_hdr-&gt;h_dest[0];
</span><span class="cm">		s_packet-&gt;mac_dest[1] = mac_hdr-&gt;h_dest[1];
</span><span class="cm">		s_packet-&gt;mac_dest[2] = mac_hdr-&gt;h_dest[2];
</span><span class="cm">		s_packet-&gt;mac_dest[3] = mac_hdr-&gt;h_dest[3];
</span><span class="cm">		s_packet-&gt;mac_dest[4] = mac_hdr-&gt;h_dest[4];
</span><span class="cm">		s_packet-&gt;mac_dest[5] = mac_hdr-&gt;h_dest[5];
</span><span class="cm">
</span><span class="cm">		s_packet-&gt;mac_source[0] = mac_hdr-&gt;h_source[0];
</span><span class="cm">		s_packet-&gt;mac_source[1] = mac_hdr-&gt;h_source[1];
</span><span class="cm">		s_packet-&gt;mac_source[2] = mac_hdr-&gt;h_source[2];
</span><span class="cm">		s_packet-&gt;mac_source[3] = mac_hdr-&gt;h_source[3];
</span><span class="cm">		s_packet-&gt;mac_source[4] = mac_hdr-&gt;h_source[4];
</span><span class="cm">		s_packet-&gt;mac_source[5] = mac_hdr-&gt;h_source[5];
</span><span class="cm">
</span><span class="cm">		s_packet-&gt;eth_proto = mac_hdr-&gt;h_proto;
</span><span class="cm">		*/</span>
		<span class="k">switch</span><span class="p">(</span><span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">eth_proto</span><span class="p">){</span>
			<span class="k">case</span> <span class="n">htons</span><span class="p">(</span><span class="mh">0x0800</span><span class="p">)</span><span class="o">:</span>	<span class="c1">// ip
</span><span class="c1"></span>				<span class="n">ip_hdr</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">iphdr</span> <span class="o">*</span><span class="p">)(</span><span class="n">buffer</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">ethhdr</span><span class="p">));</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_source</span> <span class="o">=</span> <span class="n">ip_hdr</span><span class="o">-&gt;</span><span class="n">saddr</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_dest</span> <span class="o">=</span> <span class="n">ip_hdr</span><span class="o">-&gt;</span><span class="n">daddr</span><span class="p">;</span>
				<span class="c1">// p = (char*)&amp;ip_hdr-&gt;saddr;
</span><span class="c1"></span>				<span class="c1">// printk(&#34;源 IP: %d.%d.%d.%d&#34;,
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[0], 
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[1],
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[2],
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[3]
</span><span class="c1"></span>				<span class="c1">// 	);
</span><span class="c1"></span>
				<span class="c1">// p = (char*)&amp;ip_hdr-&gt;daddr;
</span><span class="c1"></span>				<span class="c1">// printk(&#34; ==&gt; 目的 IP: %d.%d.%d.%d\n&#34;,
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[0], 
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[1], 
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[2],
</span><span class="c1"></span>				<span class="c1">// 		(u_char)p[3]
</span><span class="c1"></span>				<span class="c1">// 	);
</span><span class="c1"></span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_proto</span> <span class="o">=</span> <span class="n">ip_hdr</span><span class="o">-&gt;</span><span class="n">protocol</span><span class="p">;</span>

				<span class="k">switch</span><span class="p">(</span><span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_proto</span><span class="p">)</span> <span class="p">{</span>
					<span class="k">case</span> <span class="nl">IPPROTO_ICMP</span><span class="p">:</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">case</span> <span class="nl">IPPROTO_IGMP</span><span class="p">:</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">case</span> <span class="nl">IPPROTO_IPIP</span><span class="p">:</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">case</span> <span class="nl">IPPROTO_TCP</span><span class="p">:</span>
						<span class="n">tcp_hdr</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">tcphdr</span> <span class="o">*</span><span class="p">)(</span><span class="n">buffer</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">ethhdr</span><span class="p">)</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">iphdr</span><span class="p">));</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="n">tcp_hdr</span><span class="o">-&gt;</span><span class="n">source</span><span class="p">;</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="n">tcp_hdr</span><span class="o">-&gt;</span><span class="n">dest</span><span class="p">;</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">case</span> <span class="nl">IPPROTO_UDP</span><span class="p">:</span>
						<span class="n">udp_hdr</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">udphdr</span> <span class="o">*</span><span class="p">)(</span><span class="n">buffer</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">ethhdr</span><span class="p">)</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">iphdr</span><span class="p">));</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="n">udp_hdr</span><span class="o">-&gt;</span><span class="n">source</span><span class="p">;</span>
						<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="n">udp_hdr</span><span class="o">-&gt;</span><span class="n">dest</span><span class="p">;</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">case</span> <span class="nl">IPPROTO_RAW</span><span class="p">:</span>
						<span class="k">break</span><span class="p">;</span>
					<span class="k">default</span><span class="o">:</span>
						<span class="k">break</span><span class="p">;</span>
				<span class="p">}</span>
				<span class="c1">// printk(&#34;协议类型:&#34;);
</span><span class="c1"></span>				<span class="c1">// switch(ip_hdr-&gt;protocol) {
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_ICMP:
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;ICMP&#34;);
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_IGMP:
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;IGMP&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_IPIP:
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;IPIP&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_TCP:  
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;TCP&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_UDP:  
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;UDP&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	case IPPROTO_RAW: 
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;RAW&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// 	default: 
</span><span class="c1"></span>				<span class="c1">// 		printk(&#34;Unknown type&#34;); 
</span><span class="c1"></span>				<span class="c1">// 		break;
</span><span class="c1"></span>				<span class="c1">// }
</span><span class="c1"></span>				<span class="k">break</span><span class="p">;</span>
			<span class="k">case</span> <span class="n">htons</span><span class="p">(</span><span class="mh">0x0806</span><span class="p">)</span><span class="o">:</span> <span class="c1">// arp
</span><span class="c1"></span>				<span class="n">arp_hdr</span> <span class="o">=</span> <span class="p">(</span><span class="k">struct</span> <span class="n">arphdr</span> <span class="o">*</span><span class="p">)(</span><span class="n">buffer</span> <span class="o">+</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">ethhdr</span><span class="p">));</span>

				<span class="c1">// however #if 0 in kernel if_arp.h ip not compiled
</span><span class="c1"></span>				<span class="c1">// RFC 826  ARP packets are variable in size
</span><span class="c1"></span>				<span class="c1">// https://sites.uclouvain.be/SystInfo/usr/include/net/if_arp.h.html
</span><span class="c1"></span>				<span class="c1">// s_packet-&gt;ip_source = (__be32 *)arp_hdr-&gt;ar_sip;
</span><span class="c1"></span>
				<span class="c1">// s_packet-&gt;ip_dest = (__be32 *)arp_hdr-&gt;ar_tip;
</span><span class="c1"></span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_proto</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="k">break</span><span class="p">;</span>
			<span class="k">default</span><span class="o">:</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">ip_proto</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_source</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="n">s_packet</span><span class="o">-&gt;</span><span class="n">port_dest</span> <span class="o">=</span> <span class="mi">0</span><span class="p">;</span>
				<span class="k">break</span><span class="p">;</span>
		<span class="p">}</span>
		<span class="n">memcpy</span><span class="p">(</span><span class="n">memp</span><span class="p">,</span> <span class="n">s_packet</span><span class="p">,</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">struct_packet</span><span class="p">));</span>
		<span class="n">memp</span> <span class="o">+=</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">struct_packet</span><span class="p">);</span>
	<span class="p">}</span>

	<span class="n">kfree</span><span class="p">(</span><span class="n">buffer</span><span class="p">);</span>
	<span class="c1">// how 0 read/1 trans/2 read and trans
</span><span class="c1"></span>	<span class="n">__sys_shutdown</span><span class="p">(</span><span class="n">sock</span><span class="p">,</span> <span class="mi">2</span><span class="p">);</span>
	<span class="c1">// close(sock);
</span><span class="c1"></span>	<span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>

<span class="n">SYSCALL_DEFINE2</span><span class="p">(</span><span class="n">cap</span><span class="p">,</span> <span class="kt">char</span> <span class="o">*</span> <span class="p">,</span> <span class="n">memp</span> <span class="p">,</span> <span class="kt">int</span><span class="p">,</span> <span class="n">caplen</span><span class="p">)</span>
<span class="p">{</span>
	<span class="k">return</span> <span class="n">__sys_cap</span><span class="p">(</span><span class="n">memp</span><span class="p">,</span> <span class="n">caplen</span><span class="p">);</span>
<span class="p">}</span>



<span class="c1">// arch/x86/entry/syscalls/syscall_64.tbl
</span><span class="c1">// 335 64  cap             sys_cap
</span><span class="c1"></span>
<span class="c1">// include/linux/syscalls.h
</span><span class="c1">// asmlinkage long sys_cap(FILE *f, int caplen)
</span></code></pre></td></tr></table>
</div>
</div><p>check_syscall.c</p>
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<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="cp">#include</span> <span class="cpf">&lt;stdio.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;stdlib.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;sys/socket.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/if_ether.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;linux/in.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;sys/syscall.h&gt;</span><span class="cp">
</span><span class="cp">#include</span> <span class="cpf">&lt;unistd.h&gt;</span><span class="cp">
</span><span class="cp">#define SYSCALL_CAP 335
</span><span class="cp"></span>
<span class="k">struct</span> <span class="n">struct_packet</span> <span class="p">{</span>
	<span class="kt">unsigned</span> <span class="kt">char</span>	<span class="n">mac_dest</span><span class="p">[</span><span class="n">ETH_ALEN</span><span class="p">];</span>
	<span class="kt">unsigned</span> <span class="kt">char</span>	<span class="n">mac_source</span><span class="p">[</span><span class="n">ETH_ALEN</span><span class="p">];</span>
	<span class="n">__be16</span>		<span class="n">eth_proto</span><span class="p">;</span>
	<span class="n">__be32</span>	<span class="n">ip_source</span><span class="p">;</span>
	<span class="n">__be32</span>	<span class="n">ip_dest</span><span class="p">;</span>
	<span class="n">__u8</span>	<span class="n">ip_proto</span><span class="p">;</span>
	<span class="n">__be16</span>	<span class="n">port_source</span><span class="p">;</span>
	<span class="n">__be16</span>	<span class="n">port_dest</span><span class="p">;</span>
<span class="p">};</span>


<span class="kt">int</span> <span class="nf">main</span><span class="p">()</span>
<span class="p">{</span>
    <span class="kt">int</span> <span class="n">caplen</span> <span class="o">=</span> <span class="mi">10</span><span class="p">;</span>
    <span class="kt">int</span> <span class="n">memsize</span> <span class="o">=</span> <span class="n">caplen</span> <span class="o">*</span> <span class="k">sizeof</span><span class="p">(</span><span class="k">struct</span> <span class="n">struct_packet</span><span class="p">);</span>
    <span class="kt">char</span> <span class="o">*</span> <span class="n">memp</span> <span class="o">=</span> <span class="n">malloc</span><span class="p">(</span><span class="n">memsize</span><span class="p">);</span>
    <span class="kt">int</span> <span class="n">res</span> <span class="o">=</span> <span class="n">syscall</span><span class="p">(</span><span class="n">SYSCALL_CAP</span><span class="p">,</span> <span class="n">memp</span><span class="p">,</span> <span class="n">caplen</span><span class="p">);</span>
    
    <span class="c1">// int res = cap(memp, caplen);
</span><span class="c1"></span>    <span class="k">if</span> <span class="p">(</span><span class="n">res</span><span class="p">){</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;error:%d</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">,</span><span class="n">res</span><span class="p">);</span>
        <span class="n">exit</span><span class="p">(</span><span class="mi">1</span><span class="p">);</span>
    <span class="p">}</span>
    <span class="k">for</span> <span class="p">(</span><span class="kt">int</span> <span class="n">i</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">i</span><span class="o">&lt;</span><span class="mi">10</span><span class="p">;</span><span class="o">++</span><span class="n">i</span><span class="p">){</span>
        <span class="k">for</span> <span class="p">(</span><span class="kt">int</span> <span class="n">y</span><span class="o">=</span><span class="mi">0</span><span class="p">;</span><span class="n">y</span><span class="o">&lt;</span><span class="mi">10</span><span class="p">;</span><span class="o">++</span><span class="n">y</span><span class="p">){</span>
            <span class="n">printf</span><span class="p">(</span><span class="s">&#34;%02x &#34;</span><span class="p">,(</span><span class="kt">unsigned</span> <span class="kt">char</span><span class="p">)</span><span class="n">memp</span><span class="o">++</span><span class="p">);</span>
        <span class="p">}</span>
        <span class="n">printf</span><span class="p">(</span><span class="s">&#34;</span><span class="se">\n</span><span class="s">&#34;</span><span class="p">);</span>
    <span class="p">}</span>
    <span class="k">return</span> <span class="mi">0</span><span class="p">;</span>
<span class="p">}</span>
</code></pre></td></tr></table>
</div>
</div><h3 id="调试内核">调试内核</h3>
<p>前置：qemu及pwndbg的安装</p>
<p>gdb配合qemu调试 qemu参数-S -s启动gdbserver，gdb连上remote即可</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">qemu-system-x86_64 ... -S -s
gdb vmlinux
target remote:1234
</code></pre></td></tr></table>
</div>
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<pre tabindex="0" class="chroma"><code class="language-c" data-lang="c"><span class="kt">int</span> <span class="nf">__sys_recvfrom</span><span class="p">(</span><span class="kt">int</span> <span class="n">fd</span><span class="p">,</span> <span class="kt">void</span> <span class="n">__user</span> <span class="o">*</span><span class="n">ubuf</span><span class="p">,</span> <span class="n">size_t</span> <span class="n">size</span><span class="p">,</span> <span class="kt">unsigned</span> <span class="kt">int</span> <span class="n">flags</span><span class="p">,</span>
		   <span class="k">struct</span> <span class="n">sockaddr</span> <span class="n">__user</span> <span class="o">*</span><span class="n">addr</span><span class="p">,</span> <span class="kt">int</span> <span class="n">__user</span> <span class="o">*</span><span class="n">addr_len</span><span class="p">){</span>
	<span class="n">err</span> <span class="o">=</span> <span class="n">import_single_range</span><span class="p">(</span><span class="n">READ</span><span class="p">,</span> <span class="n">ubuf</span><span class="p">,</span> <span class="n">size</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">iov</span><span class="p">,</span> <span class="o">&amp;</span><span class="n">msg</span><span class="p">.</span><span class="n">msg_iter</span><span class="p">);</span>
    <span class="c1">// -14 kernel
</span><span class="c1"></span>    <span class="c1">// 0 user
</span><span class="c1"></span><span class="p">}</span>
<span class="mh">0xffff888005549000</span>
</code></pre></td></tr></table>
</div>
</div><p>gdb调内核发现内存写入失败</p>
<p><img src="/images/posts/%E6%93%8D%E4%BD%9C%E7%B3%BB%E7%BB%9F%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211218215217714.png" alt="image-20211218215217714" /></p>
<p><img src="/images/posts/%E6%93%8D%E4%BD%9C%E7%B3%BB%E7%BB%9F%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211218221607098.png" alt="image-20211218221607098" /></p>
<p><img src="/images/posts/%E6%93%8D%E4%BD%9C%E7%B3%BB%E7%BB%9F%E8%AF%BE%E7%A8%8B%E8%AE%BE%E8%AE%A1/image-20211218223232407.png" alt="image-20211218223232407" /></p>
<p>网络环境</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">apt-get update
<span class="c1"># 虚拟网桥工具</span>
apt-get install bridge-utils
<span class="c1"># UML（User-mode linux）工具</span>
apt-get install uml-utilities
</code></pre></td></tr></table>
</div>
</div><p>qemu默认支持的是e1000网卡，内核中需要开启如下的配置项来支持e1000</p>
<p>否则启动ifconfig -a只有一个lo设备</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">Device Drivers  ---&gt;
	<span class="o">[</span>*<span class="o">]</span> Network device support  ---&gt;
		<span class="o">[</span>*<span class="o">]</span>   Ethernet driver support  ---&gt;
			<span class="o">[</span>*<span class="o">]</span>   Intel devices
			&lt;*&gt;     Intel<span class="o">(</span>R<span class="o">)</span> PRO/1000 Gigabit Ethernet support
</code></pre></td></tr></table>
</div>
</div><pre tabindex="0"><code># 十六进制打印a开始的16个byte类型内存
x/16xb a
</code></pre><h2 id="添加文件加密">添加文件加密</h2>
<p>dm-crypt/cryptsetup</p>
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<pre tabindex="0" class="chroma"><code class="language-bash" data-lang="bash">➜  ~ cryptsetup benchmark
<span class="c1"># Tests are approximate using memory only (no storage IO).</span>
PBKDF2-sha1      <span class="m">1705001</span> iterations per second <span class="k">for</span> 256-bit key
PBKDF2-sha256    <span class="m">2111935</span> iterations per second <span class="k">for</span> 256-bit key
PBKDF2-sha512    <span class="m">1600879</span> iterations per second <span class="k">for</span> 256-bit key
PBKDF2-ripemd160  <span class="m">894689</span> iterations per second <span class="k">for</span> 256-bit key
PBKDF2-whirlpool  <span class="m">661979</span> iterations per second <span class="k">for</span> 256-bit key
argon2i       <span class="m">6</span> iterations, <span class="m">1048576</span> memory, <span class="m">4</span> parallel threads <span class="o">(</span>CPUs<span class="o">)</span> <span class="k">for</span> 256-bit key <span class="o">(</span>requested <span class="m">2000</span> ms <span class="nb">time</span><span class="o">)</span>
argon2id      <span class="m">7</span> iterations, <span class="m">1048576</span> memory, <span class="m">4</span> parallel threads <span class="o">(</span>CPUs<span class="o">)</span> <span class="k">for</span> 256-bit key <span class="o">(</span>requested <span class="m">2000</span> ms <span class="nb">time</span><span class="o">)</span>
<span class="c1">#     Algorithm |       Key |      Encryption |      Decryption</span>
        aes-cbc        128b      1068.9 MiB/s      2818.5 MiB/s
    serpent-cbc        128b        94.4 MiB/s       673.9 MiB/s
    twofish-cbc        128b       210.6 MiB/s       375.6 MiB/s
        aes-cbc        256b       846.1 MiB/s      2375.5 MiB/s
    serpent-cbc        256b        96.7 MiB/s       695.6 MiB/s
    twofish-cbc        256b       217.7 MiB/s       391.6 MiB/s
        aes-xts        256b      2632.3 MiB/s      2713.3 MiB/s
    serpent-xts        256b       673.6 MiB/s       687.9 MiB/s
    twofish-xts        256b       374.1 MiB/s       369.8 MiB/s
        aes-xts        512b      2248.3 MiB/s      2264.3 MiB/s
    serpent-xts        512b       685.4 MiB/s       693.5 MiB/s
    twofish-xts        512b       371.9 MiB/s       375.6 MiB/s
</code></pre></td></tr></table>
</div>
</div><h2 id="参考文献">参考文献</h2>
<p>[1]https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/linux-2.4.git/[source]<br />
[2]https://kernel.googlesource.com/pub/scm/linux/kernel/git/wtarreau/linux-2.4.git/[source]<br />
[3]https://github.com/torvalds/linux[kernel]<br />
[4]https://linux.cn/article-9665-1.html[kernel make]<br />
[5]https://www.linux.com/topic/desktop/how-compile-linux-kernel-0/[kernel make]<br />
[6]https://blog.csdn.net/Magic_Ninja/article/details/89058323[gcc]<br />
[7]https://stackoverflow.com/questions/34569458/error-occurred-compiling-gcc-from-source-code[gcc]<br />
[8]https://www.cnblogs.com/evilzy/archive/2008/03/30/1130179.html[kernel]<br />
[9]https://www.cnblogs.com/hellogc/p/7482066.html[qemu kernel std]<br />
[10]https://busybox.net/about.html[busybox]<br />
[11]https://blog.csdn.net/sinat_22597285/article/details/53783221?spm=1001.2014.3001.5501[qemu initrd]<br />
[12]https://blog.csdn.net/sinat_36184075/article/details/71598834[/dev/*]<br />
[13]https://fmyy.pro/2020/05/04/Kernel/Linux_Kernel_Pwn(%E4%B8%80)/#%E6%80%9D%E8%B7%AF[fmyy kernelpwn]<br />
[14]https://wiki.debian.org/Initrd[2.4&rsquo;s initrd/2.6&rsquo;s initramfs]<br />
[15]https://securitronlinux.com/debian-testing/compiling-and-installing-a-2-4-kernel-on-debian-gnu-linux-sarge/[make initrd 2.4/2.6]<br />
[16]https://www.centennialsoftwaresolutions.com/post/5-minute-user-space-hello-world-arm-cross-compile-copy-to-a-rootfs-and-run-on-qemu[busybox initramfs]<br />
[17]https://www.cnblogs.com/tsruixi/p/10777242.html [syscall hdu]<br />
[18]https://zhuanlan.zhihu.com/p/445453676 [vscode kernel dbg]<br />
[19]https://wzt.ac.cn/2021/05/28/QEMU-networking/ [qemu networking]<br />
[20]https://blog.csdn.net/gengzhikui1992/article/details/103142848 [libpcap speed]<br />
[21]https://program-think.medium.com/%E6%89%AB%E7%9B%B2-dm-crypt-%E5%A4%9A%E5%8A%9F%E8%83%BD-linux-%E7%A3%81%E7%9B%98%E5%8A%A0%E5%AF%86%E5%B7%A5%E5%85%B7-%E5%85%BC%E5%AE%B9-truecrypt-veracrypt-80a932ae3492[dm-crypt]<br />
[22]https://www.cnblogs.com/pionice/p/13288942.html [os fs blog]<br />
[23]https://github.com/744717164/OSsciByGZHU/blob/master/OSscienceDesign/OsDesignByGama.cpp [osfilesystem]<br />
[24]https://blog.csdn.net/GerZhouGengCheng/article/details/106103039 [aes-256-cbc]<br />
[25]https://blog.csdn.net/u012234115/article/details/72762045 [md5 sha256]<br />
[26]https://www.runoob.com/cplusplus/cpp-files-streams.html [c++ fstream]</p>

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      var mermaids = [];
      [].push.apply(mermaids, document.getElementsByClassName('language-mermaid'));
      mermaids.forEach(function(elem) {
        var elemParentNode = elem.parentNode;

        if (elemParentNode !== document.body) {
          elemParentNode.parentNode.insertBefore(elem, elemParentNode);
          elemParentNode.parentNode.removeChild(elemParentNode);
        }

        var newElemWrapper = document.createElement('div');
        newElemWrapper.classList.add('mermaid');
        newElemWrapper.style.padding = '34px 4px 6px';
        newElemWrapper.innerHTML = elem.innerHTML;
        elem.replaceWith(newElemWrapper);
      });
    }
    

    

    
    if (lib && lib.includes('katex')) {
      var mathElements = document.getElementsByClassName('math');
      var options = {
        delimiters: [
          { left: "$$", right: "$$", display: true },
          { left: "\\[", right: "\\]", display: true },
          { left: "$", right: "$", display: false },
          { left: "\\(", right: "\\)", display: false }
        ],
      };

      renderMathInElement(document.querySelector('.single__contents'), options);
    }
    



    
    if (lib && lib.includes('flowchartjs')) {
      
      var options = JSON.parse("{\"arrow-end\":\"block\",\"element-color\":\"black\",\"fill\":\"white\",\"flowstate\":{\"approved\":{\"fill\":\"#58C4A3\",\"font-size\":12,\"no-text\":\"n/a\",\"yes-text\":\"APPROVED\"},\"current\":{\"fill\":\"yellow\",\"font-color\":\"red\",\"font-weight\":\"bold\"},\"future\":{\"fill\":\"#FFFF99\"},\"invalid\":{\"fill\":\"#444444\"},\"past\":{\"fill\":\"#CCCCCC\",\"font-size\":12},\"rejected\":{\"fill\":\"#C45879\",\"font-size\":12,\"no-text\":\"REJECTED\",\"yes-text\":\"n/a\"},\"request\":{\"fill\":\"blue\"}},\"font-color\":\"black\",\"font-size\":14,\"line-color\":\"black\",\"line-length\":50,\"line-width\":3,\"no-text\":\"no\",\"scale\":1,\"symbols\":{\"end\":{\"class\":\"end-element\"},\"start\":{\"element-color\":\"green\",\"fill\":\"yellow\",\"font-color\":\"red\"}},\"text-margin\":10,\"x\":0,\"y\":0,\"yes-text\":\"yes\"}");
      var jsonContent = null;

      var flowchartPrefix = "language-flowchart";
      var index = 0;
      Array.prototype.forEach.call(document.querySelectorAll("[class^=" + flowchartPrefix + "]"), function(x){
          x.style.display = 'none'
          x.parentNode.style.backgroundColor = "transparent"
          jsonContent = x.innerText;

          var node0 = document.createElement('div');
          node0.id = 'flowchart' + index;
          x.parentNode.insertBefore(node0, x);

          var diagram = flowchart.parse(jsonContent);
          diagram.drawSVG("flowchart"+index, options);

          index +=1;
      });      
    }
    

    

    
    document.querySelectorAll("mjx-container").forEach(function (x) {
      x.parentElement.classList += 'has-jax'
    });
    



    
    if (lib && lib.includes('msc')) {
      
      var options = JSON.parse("{\"theme\":\"hand\"}");
      var jsonContent = null;

      var index = 0;
      var chartPrefix = "language-msc";
      Array.prototype.forEach.call(document.querySelectorAll("[class^=" + chartPrefix + "]"), function (x) {
        x.style.display = 'none'
        x.parentNode.style.backgroundColor = "transparent"
        jsonContent = x.innerText;
        var node0 = document.createElement('div');
        node0.id = 'msc' + index;
        x.parentNode.insertBefore(node0, x);
        var diagram = Diagram.parse(jsonContent);
        diagram.drawSVG("msc" + index, options);
        index += 1;
      });
    }
    



    
    if (lib && lib.includes('chart')) {
      var borderColor = "#666";
      var bgColor = "#ddd";
      var borderWidth = 2;

      Chart.defaults.global.elements.rectangle.borderWidth = borderWidth;
      Chart.defaults.global.elements.rectangle.borderColor = borderColor;
      Chart.defaults.global.elements.rectangle.backgroundColor = bgColor;

      Chart.defaults.global.elements.line.borderWidth = borderWidth;
      Chart.defaults.global.elements.line.borderColor = borderColor;
      Chart.defaults.global.elements.line.backgroundColor = bgColor;

      Chart.defaults.global.elements.point.borderWidth = borderWidth;
      Chart.defaults.global.elements.point.borderColor = borderColor;
      Chart.defaults.global.elements.point.backgroundColor = bgColor;

      var chartPrefix = "language-chart";
      var index = 0;
      var jsonContent = null;

      Array.prototype.forEach.call(document.querySelectorAll("[class^=" + chartPrefix + "]"), function (x) {
        x.style.display = 'none'
        x.parentNode.style.backgroundColor = "transparent"
        jsonContent = x.innerText;
        var node0 = document.createElement('canvas');
        var source = null;
        node0.height = 200;
        node0.style.height = 200;
        node0.id = 'myChart' + index;
        source = JSON.parse(jsonContent);
        x.parentNode.insertBefore(node0, x);
        var ctx = document.getElementById('myChart' + index).getContext('2d');
        var myChart = new Chart(ctx, source);
        index += 1;
      });            
    }
    



    
    if (lib && lib.includes('wavedrom')) {
      var wavePrefix = "language-wave";
      var index = 0;
      var jsonContent = null;
      
      Array.prototype.forEach.call(document.querySelectorAll("[class^=" + wavePrefix + "]"), function (x) {
        x.style.display = 'none'
        x.parentNode.style.backgroundColor = "transparent"
        jsonContent = x.innerText;
        var node0 = document.createElement('div');
        var source = null;
        node0.id = 'WaveDrom_Display_' + index;
        source = JSON.parse(jsonContent);
        x.parentNode.insertBefore(node0, x);
        WaveDrom.RenderWaveForm(index, source, "WaveDrom_Display_");
        index += 1;
      });
    }
    



    
    if (lib && lib.includes('viz')) {
      var vizPrefix = "language-viz-";
      Array.prototype.forEach.call(document.querySelectorAll("[class^=" + vizPrefix + "]"), function (x) {
        x.style.display = 'none'
        x.parentNode.style.backgroundColor = "transparent"
        var engine;
        x.getAttribute("class").split(" ").forEach(function (cls) {
          if (cls.startsWith(vizPrefix)) {
            engine = cls.substr(vizPrefix.length);
          }
        });
        var viz = new Viz();
        viz.renderSVGElement(x.innerText, { engine: engine })
          .then(function (element) {
            element.style.width = "100%";
            x.parentNode.insertBefore(element, x);
          })
      });
    }
    
    
  }
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